This invention relates to explosives, particularly to explosive compositions based upon ammonium nitrate.
Traditional general-purpose explosives comprise trinitrotoluene (TNT), which has several disadvantages. It is a Class-A explosive, requiring special mixing and handling procedures and storage facilities, all accordingly increasing the cost of use. The preparation of this explosive is through nitrate substitution of toluene by a mixed acid consisting of concentrated nitric acid and sulphuric acid. The cost of concentrated nitric acid is moderately expensive and any excess nitric acid in the product destabilizes the explosive and presents corrosion problems. Trinitrotoluene is not water soluble and bomb disposal cannot be done economically by steam or hot water.
It is known to produce cast high explosive compositions by solidification of a molten mixture of ammonium nitrate (AN) and ethylenediamine dinitrate (EDDN). A binary mixture of ethylenediamine dinitrate and ammonium nitrate is water soluble, thereby having several advantages over trinitrotoluene such as safer storage as a non-explosive water solution and cheaper disposal. However, the binary mixture has a high melting point, has stability problems, and is expensive.
It is known to add potassium nitrate (KN) to the AN/EDDN mixture to improve its stability. The problems associated with the binary mixture remain and the amount of chloride impurities is increased by the additional chloride impurities found in potassium nitrate (KN). If these impurities are not removed, the explosive has serious corrosion problems. If the impurities are removed the cost of the explosive increases greatly. The present method of making the ternary mixture is to mix solid ethylenediamine dinitrate, ammonium nitrate and potassium nitrate. Ethylenediamine dinitrate is not commercially availabe in large quantities and is expensive. Industrial grade ammonium nitrate and potassium nitrate are too impure to be used without the additional expense of purification. Dry mixing three explosives to form an explosive mixture requires special procedures and precautions, causing the cost of the process to increase significantly.
Other explosives compositions based upon ammonium nitrate include AN/fuel oil, AN/TNT/RDX (cyclotrimethylenetrinitramine), AN/ammonium salt of a nitroazole/RDX, AN/EDDN/KN/NQ (nitroguanidine) and the like.
It is known that ammonium nitrate is a hazardous material to manufacture on an industrial scale, to handle in large amounts, and to store in great masses, especially for relatively long periods of time. It is also known that the shock sensitivity of ammonium nitrate increases seriously after exposure to a few temperature cycles through the 32.3.degree. C. (90.degree. F.) transition point. (Up to 32.3.degree. C. the stable crystal form is orthorhombic bipyrimidal; from 32.3.degree. C. to 84.degree. C. the stable crystal form is orthorhombic).
Military explosive formulations have consisted primarily of eutectic mixtures of fuel-rich components such as EDDN, quanidinium nitrate or NQ with oxidizer-rich components such as AN, sodium nitrate, KN or calcium nitrate. Commercial compositions have consisted primarily of gels, slurries or aqueous emulsions of AN with various fuels and additives.
The high explosive eutectic formulations utilized for military applications have typically been plagued by problems relating to large critical diameters, performance variability as a response to particle size and fractional crystallization, and sensitivity to shock. The non-ideal behavior of composite explosive is believed to be a consequence of the relatively great distances, on the atomic and molecular scale, between the fuel-rich and oxidizer-rich components. These distances can exceed 10.sup.5 Angstroms between crystal centers. This is in contrast to mono-molecular (ideal) explosive in which reacting atoms are separated by less than 10.sup.1 Angstroms.
It is well known that improvements in explosive properties, such as performance and critical diameter, can be achieved through greater fuel oxidizer intimacy. Traditional methods for attaining this increased intimacy have relied on reducing particle size through the use of exact eutectic formulations or emulsification.
Accordingly, it is an object of this invention to provide a novel explosive composition based upon ammonium nitrate.
Other objects and advantages of the present invention will be apparent to those skilled in the art from a reading of the following description of the invention.